Sulfur compound and use thereof

ABSTRACT

This invention provides sulfur-containing (meth)acrylic ester compounds each of which is represented by the following formula (1);                    
     wherein R 1  and R 2  each independently represent a hydrogen atom or an alkyl group or may be fused together to form a ring, R 3  represents a hydrogen atom or a methyl group, X 1  represents an oxygen atom or a sulfur atom, m stands for an integer of from 0 to 3, and n stands for an integer of from 1 to 4, polymerizable compositions comprising the sulfur-containing (meth)acrylic acids, and cured products and optical parts obtained by polymerizing the polymerizable compositions. The sulfur-containing (meth)acrylic ester compounds according to the present invention are very useful, as monomers for photocurable, polymerizable compositions, in applications such as optical materials and dental materials. The optical parts obtained by curing the polymerizable compositions are excellent in optical properties, thermal properties and mechanical properties and are also good in productivity.

This application is a 371 of PCT/JP00/05368 with international filingdate of Aug. 10, 2000.

TECHNICAL FIELD

This invention relates to a sulfur-containing (meth)acrylic estercompound. The present invention is also concerned with a polymerizablecomposition comprising the sulfur-containing (meth)acrylic estercompound, and also with an optical part obtained by polymerizing thepolymerizable composition.

The sulfur-containing (meth)acrylic ester compound according to thepresent invention has a characteristic feature in molecular structurethat contains a cyclic thioacetal structure in its molecule, and isuseful as a monomer for a photocurable, polymerizable composition. Theoptical part obtained by curing the polymerizable composition isexcellent in optical properties, thermal properties and mechanicalproperties, is good in productivity and has high refractive index, sothat it is useful as various plastic lenses represented by correctionaleyeglass lenses, substrates for optical information recording media,plastic substrates for liquid crystal cells, coating materials foroptical fibers, and the like.

BACKGROUND ART

Inorganic glass is excellent in various physical properties as typifiedby excellent transparency and small optical anisotropy, and therefore,is used as a transparent optical material in a wide variety of fields.Nonetheless, it involves problems such as heavy weight, fragility andpoor productivity, and in recent years, developments of optical resinsas replacements for inorganic glass are actively under way.

As an optical resin, a fundamentally important property is transparency.Industrial optical resins known to date to have good transparencyinclude polymethyl methacrylate (PMMA), bisphenol A polycarbonate(BPA-PC), polystyrene (PS), methyl methacrylate-styrene copolymer (MS),styrene-acrylonitrile copolymer (SAN), poly(4-methylpentene-1) (TPX),polycycloolefins (COPs), polydiethylene glycol bis(allyl carbonate)(EGAC), polythiourethanes (PTUs), and the like.

PMMA is excellent in transparency and weatherability and is also good inmoldability. It, however, involves drawbacks in that it has a refractiveindex (nd) as low as 1.49 and high water absorption property.

BPA-PC has a large chromatic aberration so that a limitation is imposedon its application fields, although it is excellent in transparency,heat resistance, impact resistance and high refraction properties.

PS and MS are excellent in moldability, transparency, low waterabsorption property, and high refraction properties. They are, however,inferior in impact resistance, weatherability and heat resistance sothat they have not found any substantial practical utility as opticalresins.

SAN is relatively high in refractive index and its mechanical propertiesare considered to be well-balanced. However, SAN is somewhat defectivein heat resistance (heat distortion temperature: 80 to 90° C.) andpractically, is not used as an optical resin.

TPX and COPs are excellent in transparency and heat resistance, and havelow water absorption property. They are, however, accompanied byproblems in that they are low in refractive index (nd: 1.47 to 1.53) andare poor in impact resistance, gas barrier property and dyeability.

EGAC is a thermosetting resin available from diethylene glycol bis(allylcarbonate) as a monomer, and is used most widely for general-purposeeyeglass lenses. Although it is excellent in transparency and heatresistance and is extremely small in chromic aberration, it hasdrawbacks in that it is low in refractive index (nd=1.50) and isinferior in impact resistance.

PTUs are thermosetting resins each of which are obtained by a reactionbetween a diisocyanate compound and a polythiol compound, and are usedmost widely for eyeglass lenses of high refractive index. They areextremely good materials for their outstanding transparency, impactresistance, high refractive properties and their small chromicaberration. They are, however, deficient only in that they require longthermopolymerization molding time (1 to 3 days), and are stillaccompanied by an unsolved problem in productivity.

With a view to achieving polymerization and curing in a short time toincrease their productivity, certain production processes have beenproposed, including photopolymerization of a bromine- orsulfur-containing acrylic ester to obtain an optical lens (e.g., JP4-161410 A, JP 3-217412 A) and use of a (meth)acrylic ester compoundhaving a sulfur-containing alicyclic structure for the production of anoptical lens (e.g., JP 3-215801 A).

These processes make it possible to achieve polymerization in a shorttime, but the resulting resins are by no means satisfactory for opticalparts. Described specifically, when these resins are used as eyeglasslenses, for example, those having high refractive indexes involveproblems in that they are brittle and susceptible to breakage and arehigh in specific gravity. There is, accordingly, a strong desire for thedevelopment of a material free of these problems.

As has been described above, it is the current circumstance that each ofthe conventional optical resins still has one or more drawbacks to besolved although it has certain excellent properties. Under the foregoingsituation, it is the current circumstance that a keen desire exists forthe development of an optical resin excellent in optical properties,mechanical properties and thermal properties and high in productivityand refractive index.

DISCLOSURE OF THE INVENTION

An object of the present invention is, therefore, to solve theabove-described drawbacks of the conventional optical resins, and toprovide a monomer as a raw material for an optical material excellent inoptical properties, mechanical properties and thermal properties andhigh in productivity and refractive index and also to provide anintermediate for the monomer.

The present inventors have proceeded with an extensive investigation toachieve the above-described object and as a result, have reached thepresent invention. Specifically, the present invention relates to asulfur-containing (meth)acrylic ester compound represented by thefollowing formula (1):

wherein R₁ and R₂ each independently represent a hydrogen atom or analkyl group or may be fused together to form a ring, R₃ represents ahydrogen atom or a methyl group, X₁ represents an oxygen atom or asulfur atom, m stands for an integer of from 0 to 3, and n stands for aninteger of from 1 to 4.

The present invention also relates to a polymerizable compositioncomprising the sulfur-containing (meth)acrylic ester compoundrepresented by formula (1), a cured product obtained by polymerizing thepolymerizable composition, and further, an optical part comprising thecured product.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention will hereinafter be described in detail.

The sulfur-containing (meth)acrylic ester compound according to thepresent invention, which is represented by formula (1), is a novelcompound, and is a (meth)acrylic ester characterized by the possessionof a cyclic thioacetal structure in the moiety of the ester group.

In formula (1), R₁ and R₂ each independently represent a hydrogen atomor an alkyl group. As an alternative, R₁ and R₂ may be fused together toform a ring.

Each of the substituents R₁ and R₂ may preferably be a hydrogen atom oran alkyl group having 1 to 4 carbon atoms, with a hydrogen atom, amethyl group or an ethyl group being more preferred. When R₁ and R₂ arefused together to form a ring, the ring may be preferably a cycloalkanering, more preferably a cycloalkane ring having 5 to 7 carbon atoms,still more preferably a cyclohexane ring.

In formula (1), m is an integer of from 0 to 3, preferably an integer offrom 0 to 2, more preferably an integer of 0 or 1.

In formula (1), n is an integer of from 1 to 4, preferably an integer offrom 1 to 3, more preferably an integer of 1 or 2.

In formula (1), X₁ represents an oxygen atom or a sulfur atom. In viewof a high refractive index required upon using as a lens resin, X₁ ispreferably a sulfur atom.

As specific examples of the sulfur-containing (meth)acrylic estercompound represented by formula (1) according to the present invention,the compounds shown below in Table 1 can be exemplified.

TABLE 1 Illustrative Compound No. Structural formula 1-1

1-2

1-3

1-4

1-5

1-6

1-7

1-8

1-9

1-10

1-11

1-12

1-13

1-14

1-15

1-16

1-17

1-18

1-19

1-20

1-21

1-22

1-23

1-24

1-25

1-26

1-27

1-28

1-29

1-30

1-31

1-32

1-33

1-34

1-35

1-36

1-37

1-38

1-39

1-40

1-41

1-42

1-43

1-44

1-45

1-46

1-47

1-48

1-49

1-50

1-51

1-52

1-53

1-54

1-55

1-56

These sulfur-containing (meth)acrylic ester compounds represented byformula (1) according to the present invention can each be produced byconducting, on a compound represented by the following formula (2-a) orthe following formula (2-b), desired one of various known esterificationprocesses (or thioesterification processes) typified specifically by:

(1) a process in which a (meth)acrylic acid or the like is reacted; and

(2) a process in which a halopropionic ester compound (for example,3-chloropropionic acid, 3-bromopropionic acid,3-chloro-2-methylpropionic acid, 3-bromo-2-methylpropionic acid, or thelike) or an acid halide thereof is reacted to form a halopropionic esterderivative, followed by the dehydrohalogenation of the derivative intothe (meth)acrylic ester.

 wherein R₁, R₂, m and n have the same meanings as defined above.

Among the processes described above, the latter process (2) is morepreferred as a process for producing each sulfur-containing(meth)acrylic ester compound represented by formula (1) according to thepresent invention.

As a most representative example of the above-mentioned processes, amore detailed description will hereinafter be made firstly about aprocess in which a sulfur-containing compound represented by formula(2-a) or formula (2-b) and a (meth)acrylic acid or the like[(meth)acrylic acid, an ester derivative, or an acid halide thereof] arereacted.

Specifically, a known process, for example, a process similar to thatdisclosed in J. Org. Chem., 45, 5364 (1980) or Eur. Polym. J., 19, 399(1983) can be used as the above process.

Illustrative is:

(1) a process in which an acid halide of (meth)acrylic acid is caused toact on a sulfur-containing compound represented by formula (2-a) orformula (2-b) under stirring in the presence of a base by a proceduresuch as dropwise addition of the acid halide;

(2) a process in which a sulfur-containing hydroxy compound representedby formula (2-b) and (meth)acrylic acid are subjected to a dehydratingreaction in the presence of a catalyst; or

(3) a process in which a sulfur-containing hydroxy compound representedby formula (2-b) and a (meth)acrylic ester derivative [for example, analkyl (meth)acrylate such as methyl (meth)acrylate, ethyl (meth)acrylateor butyl (meth)acrylate] are subjected to an ester interchange reactionin the presence of a catalyst (acid catalyst or base catalyst).

No particular limitation is imposed on the amount of the (meth)acrylicacid or the like [(meth)acrylic acid, an ester derivative thereof, or anacid halide thereof] which is caused to act on the sulfur-containingcompound represented by formula (2-a) or formula (2-b) in theabove-described reaction. In general, however, the (meth)acrylic acid orthe like may be used in a proportion of from 0.1 to 5 moles, with 0.25to 2.5 moles being preferred and 0.4 to 1.5 moles being more preferred,all per mole of the sulfur-containing compound.

The reaction can be conducted in a solventless manner, or can beconducted in a solvent which is inert to the reaction. Examples of sucha solvent can include hydrocarbon solvents such as n-hexane, benzene andtoluene; ketone solvents such as acetone, methyl ethyl ketone and methylisobutyl ketone; ester solvents such as ethyl acetate and butyl acetate;ether solvents such as diethyl ether, tetrahydrofuran and dioxane;halogenated solvents such as dichloromethane, chloroform, carbontetrachloride, 1,2-dichloroethane and Perclene; and polar solvents suchas acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide andN,N-dimethylimidazolidinone. Two or more of these solvents may be usedwithout development of inconvenience.

No particular limitation is imposed on the reaction temperature. Thereaction should, however, be conducted at such a temperature thatneither the (meth)acrylic acid or the like as a raw material nor thesulfur-containing (meth)acrylic ester compound as a reaction product isallowed to undergo polymerization. In general, the reaction temperaturemay be in a range of from −78 to 150° C., with −20 to 120° C. beingpreferred and 0 to 100° C. being more preferred.

The reaction time is also dependent upon the reaction temperature. Ingeneral, however, the reaction time may range from several minutes to100 hours, with 30 minutes to 50 hours being preferred and 1 to 20 hoursbeing more preferred. As an alternative, the reaction can be terminatedat a desired rate of reaction while monitoring the rate of reaction by aknown analyzing means (for example, liquid chromatography, thin layerchromatography, IR or the like).

Upon producing the sulfur-containing (meth)acrylic ester compoundaccording to the present invention by the reaction betweensulfur-containing compound represented by formula (2-a) or formula (2-b)and the acid halide of (meth)acrylic acid, hydrogen halide (for example,hydrogen chloride or the like) is byproduced. For example, an organicbase such as triethylamine, pyridine, picoline, dimethylaniline,diethylaniline, 1,4-diazabicyclo[2.2.2] octane (DABCO) or1,8-diazabicyclo[5.4.0]undeca-7-ene (DBU) or an inorganic base such assodium hydrogencarbonate, sodium carbonate, potassium carbonate, lithiumcarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide ormagnesium oxide may, therefore, be used as a dehydrohalogenating agent.

Although no particular limitation is imposed on the amount of such adehydrohalogenating agent to be used, it may be used in a proportion offrom 0.05 to 10 moles, preferably from 0.1 to 5 moles, more preferablyfrom 0.5 to 3 moles per mole of the sulfur-containing compoundrepresented by formula (2).

Upon producing the sulfur-containing (meth)acrylic ester compoundrepresented by formula (1) according to the present invention by thedehydrating reaction between the sulfur-containing hydroxy compoundrepresented by formula (2-b) and (meth)acrylic acid, use of desired oneof various known esterification catalysts is preferred. Illustrative ofthe catalysts are mineral acids (for example, hydrochloric acid,sulfuric acid, nitric acid, boric acid, phosphoric acid, and the like);organic acids (for example, methanesulfonic acid, benzenesulfonic acid,p-toluenesulfonic acid, trifluoromethanesulfonic acid, and the like);and Lewis acids (for example, boron trifluoride, aluminum trichloride,titanium tetrachloride, titanium dichloride, tin dichloride, tintetrachloride, and the like).

No particular limitation is imposed on the amount of such a catalyst tobe used. In general, however, it may be used preferably in a proportionof from 0.001 to 50 wt. %, more preferably in a proportion of from 0.01to 30 wt. % based on the reaction feed mixture.

For the acceleration of the progress of the reaction, it is preferred toremove byproduced water from the system. Examples of a method foreffecting this removal include azeotropic dehydration by use of one ofthe above-exemplified solvents, said one solvent being capable offorming an azeotropic mixture (for example, a hydrocarbon solvent suchas benzene, toluene or xylene); use of a dehydrating agent such asmolecular sieve; and combined use of these methods.

Among the above-mentioned processes, the process—in which thesulfur-containing (meth)acrylic ester compound represented by formula(1) is produced by reacting the halopropionic ester compound representedby formula (2-a) or formula (2-b) with the halopropionic acid or itsacid halide to form a halopropionic ester compound and thendehydrohalogenating the halopropionic ester compound—can be typified,for example, by the process disclosed in JP 10-67736 A or the like.

Upon producing the sulfur-containing (meth)acrylic ester compoundrepresented by formula (1) according to the present invention, use of apolymerization inhibitor for the prevention of polymerization of thereaction product during the reaction or after the reaction is preferred.As examples of such a polymerization inhibitor, a variety of knowncompounds such as 4-methoxyphenol, hydroquinone and phenothiazine can bementioned. No particular limitation is imposed on the amount of thepolymerization inhibitor to be used. In general, however, thepolymerization inhibitor may be used in a proportion of from 0.01 to 5wt. %, preferably from 0.05 to 3 wt. % based on the reaction feedmixture or the reaction product in the reaction system.

After completion of the reaction, the reaction product, i.e., thesulfur-containing (meth)acrylic ester compound represented by formula(1) according to the present invention is post-treated and isolated byknown procedure and treatment methods (typically, neutralization,extraction into solvent, washing with water, separation into layers,removal of solvent by distillation, etc.). If necessary, thethus-obtained sulfur-containing (meth)acrylic ester compound representedby formula (1) may be separated and purified by a known method (forexample, distillation, recrystallization, chromatography or the like) toisolate as a high-purity compound.

The compound represented by formula (2-a) or (2-b), namely, thehydroxyl-containing compound (2-b) or the thiol-containing compound(2-a) can be appropriately produced by converting the halogen atom in acyclic thioacetal compound, which is represented by the below-describedformula (2-c), in accordance with a known synthetic chemical procedure,for example, by subjecting the halogen atom to alkaline hydrolysis toconvert the same into a hydroxyl group or by causing thiourea to act onthe halogen atom to form a thiouronium salt and then subjecting it toalkaline treatment to form a thiol group.

wherein R₁, R₂, m and n have the same meanings as defined above, and Xrepresents a halogen atom.

Further, the conversion from the halogen derivative represented byformula (2-c) into the thiol group can be appropriately practiced by aknown process, for example, by the process disclosed in Journal ofOrganic Chemistry, 27, 93-95 (1962) or Organic Synthesis, IV, 401-403(1963). Described specifically, according to such a representativeprocess, the compound of formula (2-a) can be appropriately produced byreacting thiourea to X (i.e., halogen atom) in formula (2-c) and thenhydrolyzing the thus-formed group with a base such as aqueous ammonia orsodium hydroxide.

The sulfur-containing compound represented by formula (2-c), which isuseful as a raw material in the present invention, can be appropriatelyproduced typically by reacting a dithiol represented by the followingformula (4) with an aldehyde represented by the following formula (3) ora derivative thereof in the presence of an acid catalyst.

wherein X₃ represents a halogen atom, and n stands for an integer offrom 1 to 4.

wherein R₁, R₂ and m have the same meanings as defined above.

A more detailed description will hereinafter be made firstly about theprocess in which the compound represented by formula (2-c) is producedby reacting the dithiol represented by formula (4) to the aldehyderepresented by formula (3) or the like in the presence of the acidcatalyst.

Illustrative of the aldehyde represented by formula (3) or itsderivative are: haloalkyl aldehydes such as chloroacetaldehyde,3-chloropropionaldehyde, 3-bromopropionaldehyde, 4-chlorobutyraldehyde,and 4-bromobutyraldehyde; and dialkyl acetal derivatives or cyclicalkylene acetal derivatives or the like of haloalkyl aldehydes, such as2-chloroacetaldehyde dimethyl acetal, 2-chloroacetaldehyde diethylacetal, 2-chloropropionaldehyde dimethyl acetal, 2-chloropropionaldehydediethyl acetal, 2-bromopropion-aldehyde diethyl acetal,2-bromopropionaldehyde ethylene acetal [or2-(2′-bromoethyl)-1,3-dioxolane], and 2-bromo-propionaldehydetrimethylene acetal [or 2-(2′-bromo-ethyl)-1,3-dioxane].

Illustrative of the dithiol derivative represented by formula (4) are:

linear alkanedithiols such as ethanedithiol, 1,2-propanedithiol,1,3-propanedithiol, 1,2-butanedithiol, 1,3-butanedithiol,1,4-butanedithiol, 1,2-pentanedithiol, 1,3-pentanedithiol,1,4-pentanedithiol, 1,2-hexanedithiol, 1,3-hexanedithiol,1,4-hexanedithol, 1,2-heptanedithol, 1,2-octanedithiol,1,2-nonanedithiol, and 1,2-decanedithiol; and

cycloalkanedithiols such as cyclopentane-1,2-dithiol andcyclohexane-1,2-dithiol.

No particular limitation is imposed on the amount of the dithiolrepresented by formula (4) which is to be used upon producing thecompound of formula (2-c) by reacting the dithiol represented by formula(4) with the aldehyde represented by formula (3) or its derivative. Ingeneral, however, the dithiol represented by formula (4) may be used ina proportion of from 0.5 to 5 moles per mole of the aldehyde representedby formula (3) or its derivative, with 0.8 to 2 moles being preferredand 0.9 to 1.2 moles being more preferred.

In such a reaction, the reaction may be conducted under solventlessconditions or in the presence of a catalyst such as a protonic acid, forexample, a mineral acid (e.g., hydrochloric acid or sulfuric acid) or anorganic acid (e.g., acetic acid or propionic acid), or a Lewis acid. Inview of the reaction temperature, reaction time and the like, it ispreferred to conduct the reaction in the presence of the catalyst forthe purpose of accelerating the reaction.

Illustrative of such reaction catalysts are:

protonic acids such as sulfuric acid, hydrochloric acid, hydrobromicacid, nitric acid, acetic acid, propionic acid, methanesulfonic acid,trifluoromethanesulfonic acid, and p-toluenesulfonic acid; and

Lewis acids such as titanium trichloride, titanium tetrachloride, tindichloride, tin tetrachloride, boron trifluoride-ether complexes.

No particular limitation is imposed on the amount of such a reactioncatalyst to be used. In general, however, the reaction catalyst may beused in a proportion of from 0.001 mole to 20 moles per mole of thealdehyde represented by formula (3) or its derivative, with 0.01 mole to10 moles being preferred and 0.1 mole to 5 moles being more preferred.These reaction catalysts may be used either singly or in combination.

The reaction can be conducted either in a solventless manner or in thepresence of a solvent. When a solvent is used, no particular limitationis imposed on the solvent insofar as it is inert to the reaction.Examples of the solvent include hydrocarbon solvents such as benzene,toluene and xylene; halogenated solvents such as methylene chloride,chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene; andether-type solvents such as diethyl ether, tetrahydrofuran, dioxane anddiethylene glycol dimethyl ether. These solvents may be used eithersingly or in combination.

No particular limitation is imposed on the amount of the reactionsolvent to be used. From the standpoint of production efficiency and thelike, however, it is not preferred to use the reaction solvent in anexcessively large amount. The reaction solvent may, therefore, be usedgenerally in a weight proportion not greater than 300 times, preferablyin a weight proportion not greater than 100 times the aldehyderepresented by formula (3) or its acetal derivative.

The reaction may be conducted either under the surrounding atmosphere orunder an inert gas atmosphere. To control coloration or the like of thereaction production, however, it is preferred to conduct the reactionunder an inert gas atmosphere such as nitrogen or argon.

No particular limitation is imposed on the reaction temperature. Ingeneral, however, it is preferred to conduct the reaction in a range offrom 0° C. to the boiling point of the solvent.

The reaction time varies depending upon the reaction temperature. Ingeneral, the reaction may be conducted for a time ranging from severalminutes to several tens of hours. The end point of the reaction can bedetermined by monitoring the reaction with a known analysis means (forexample, liquid chromatography, thin-layer chromatography, IR or thelike).

The sulfur-containing compounds represented by formulas (2-a) to (2-c)can each be isolated by subjecting the reaction product to usualpost-treatment operations (for example, neutralization, filtration,extraction in a solvent, washing with water, separation into layers,removal of the solvent by distillation). By known operations andpurification methods (for example, distillation, recrystallization,column chromatography, treatment with activated carbon, and the like),their purity can be increased further if necessary.

As specific examples of the sulfur-containing compounds represented byformulas (2-a) to (2-c), the compounds shown below in Table 2 can beexemplified.

TABLE 2 Illustrative Compound No. Structural formula 2-1

2-2

2-3

2-4

2-5

2-6

2-7

2-8

2-9

2-10

2-11

2-12

2-13

2-14

2-15

2-16

2-17

2-18

2-19

2-20

2-21

2-22

2-23

2-24

2-25

2-26

2-27

2-28

2-29

2-30

2-31

2-32

2-33

2-34

2-35

2-36

2-37

2-38

2-39

2-40

2-41

2-42

2-43

2-44

A description will next be made in detail about the polymerizablecomposition which comprises the sulfur-containing (meth)acrylic estercompound represented by formula (1) according to the present invention.

The polymerizable composition according to the present inventioncontains, as essential components, the sulfur-containing (meth)acrylicester compound represented by formula (1) according to the presentinvention and a photo- and/or thermopolymerization initiator. Here, theabove-described, sulfur-containing, unsaturated carboxylic estercompounds may be used singly, or a plurality of differentsulfur-containing (meth)acrylic ester compounds may be used incombination without developing inconvenience.

In addition to the sulfur-containing (meth)acrylic ester compoundrepresented by formula (1), the polymerizable composition according tothe present invention may also contain a known polymerizable compound(photo- or thermopolymerizable monomer, oligomer or the like) to extentnot impairing the desired effects as needed without developinginconvenience.

No particular limitation is imposed on the amount of thesulfur-containing (meth)acrylic ester compound represented by formula(1) and contained in the above-described polymerizable composition. Ingeneral, however, it may be contained in a proportion of 10 wt. % ormore, preferably 20 wt. % or more, more preferably 30 wt. % or more,still more preferably 50 wt. % or more based on the whole polymerizablecomposition.

No particular limitation is imposed on the polymerization initiator foruse in the polymerizable composition according to the present invention.Various known thermopolymerization initiators or photo-polymerizationinitiators can be used. Illustrative of photopolymerization initiatorsare benzoin, benzil, benzoin methyl ether, benzoin isopropyl ether,acetophenone, 1,1-dimethoxy-1-phenylacetophenone,1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone,2-hydroxy-2-methyl-1-phenylpropan-1-one,2-methyl-1-(4-methylthiophenyl)-2-morpholinolpropan-1-one,N,N-dimethylaminoacetophenone, 2-methylanthraquinone,2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone,2-amylanthraquinone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone,2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, acetophenonedimethylketal, benzophenone, 4-methylbenzophenone,4,4′-dicyclobenzophenone, 4,4′-bisdiethylaminobenzophenone, andMichler's ketone. They can be used either singly or in combination.

The photopolymerization initiator may be used in a proportion of from0.001 to 50 parts by weight, preferably from 0.01 to 30 parts by weight,more preferably from 0.1 to 10 parts by weight, still more preferablyfrom 0.2 to 5 parts by weight per 100 parts by weight of thesulfur-containing (meth)acrylic ester compound represented by formula(1).

Illustrative of the thermopolymerization initiators are peroxides suchas benzoyl peroxide, p-chlorobenzoyl peroxide, diisopropylperoxycarbonate, di-2-ethylhexyl peroxycarbonate and tert-butylperoxypivalate; and azo compounds such as azobisisobutyronitrile.

The thermopolymerization initiator may be used in a proportion of from0.001 to 50 parts by weight, preferably from 0.01 to 30 parts by weight,more preferably from 0.1 to 10 parts by weight, still more preferablyfrom 0.2 to 5 parts by weight per 100 parts by weight of thesulfur-containing (meth)acrylic ester compound represented by formula(1).

Examples of the known polymerizable compound as a polymerizable compoundusable in the polymerizable composition according to the presentinvention, said known polymerizable compound being other than thesulfur-containing (meth)acrylic ester compound represented by formula(1), include:

monofunctional or polyfunctional (meth)acrylates such as:

methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, ethylcarbitol (meth)acrylate, lauryl (meth)acrylate,tetracyclododecyl (meth)acrylate, phenoxyethyl (meth)acrylate,nonylphenoxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate,isobornyl (meth)acrylate, N-n-butyl-O-(meth)acryloyloxy-ethyl carbamate,acryloylmorpholine, trifluoroethyl (meth)acrylate, tribromobenzyl(meth)acrylate, and perfluorooctylethyl (meth)acrylate,

ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate,neopentyl glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate,

triethylene glycol di(meth)acrylate, tripropylene glycoldi(meth)acrylate, polyethylene glycol di(meth)acrylate, andpolypropylene glycol di(meth)acrylate,

2,2-bis(4-acryloyloxyphenyl)propane,2,2-bis(4-methacryloyloxyphenyl)propane,

bis(4-acryloyloxyphenyl)methane, bis(4-methacryloyloxyphenyl)methane,4,4′-bis(acryloyloxy)-diphenyl sulfide,4,4′-bis(methacryloyloxy)diphenyl sulfide,2,2-bis[4-(acryloyloxyethoxy)phenyl]propane,2,2-bis[4-(methacryloyloxyethoxy)phenyl]propane,2,2-bis[4-(2-acryloyloxypropoxy)phenyl]propane,2,2-bis[4-(2-methacryloyloxypropoxy)phenyl]propane,bis[4-(acryloyloxyethoxy)phenyl]methane,bis[4-(methacryloyloxyethoxy)phenyl]methane,bis[4-(2-acryloyloxypropoxy)phenyl]methane, andbis[4-(2-methacryloyloxypropoxy)phenyl]methane,

4,4′-bis(2-acryloyloxyethoxy)diphenyl sulfide,4,4′-bis(2-methacryloyloxyethoxy)diphenyl sulfide,4,4′-bis(2-acryloyloxypropoxy)diphenyl sulfide, and4,4′-bis(2-methacryloyloxypropoxy)diphenyl sulfide,

4,4′-bis(2-acryloyloxyethoxy)diphenylsulfone, 4,4′-bis(2-methacryloyloxyethoxy)diphenylsulfone,4,4′-bis(2-acryloyloxypropoxy)diphenylsulfone, and4,4′-bis(2-methacryloyloxypropoxy)diphenylsulfone,

2,2-bis(4-hydroxyphenyl)propane-ethylene oxide or propylene oxide adductdi(meth)acrylate, bis(4-hydroxyphenyl)methane-ethylene oxide orpropylene oxide adduct di(meth)acrylate, and 4,4′-dihydroxyphenylsulfide-ethylene oxide or propylene oxide adduct di(meth)acrylate,

trimethylolpropane tri(meth)acrylate, dipentaerythritol pentacrylate,pentaerythritol triacrylate, pentaerythritol tetracrylate, ditrimethyloltetracrylate, dipentaerythritol hexacrylate, 2-(meth)acryloyloxyethyltrisisocyanate, and (meth)acryloyloxypropyl tris(methoxy)silane;

epoxy (meth)acrylates obtained by causing (meth)acrylic acid compoundsto act on various known monovalent, divalent or higher valent epoxycompounds, such as:

phenol glycidyl ether, ethylene glycol diglycidyl ether, propyleneglycol diglycidyl ether, resorcin diglycidyl ether, hydroquinonediglycidyl ether, bis(4-hydroxyphenyl)methane (common name: bisphenol F)diglycidyl ether, 2,2-bis(4-hydroxyphenyl)propane (common name:bisphenol A) diglycidyl ether, 4,4′-bishydroxyphenyl sulfide diglycidylether, 4,4′-bishydroxyphenylsulfone (common name: bisphenol S)diglycidyl ether, 4,4′-biphenol diglycidyl ether,3,31,5,5′-tetramethyl-4,4′-biphenol diglycidyl ether, andtris(2,3-epoxypropyl) isocyanurate;

epoxy (meth)acrylates obtained by causing (meth)acrylic acid compoundsto act on various known epoxy resins, such as:

epoxy resins of the phenolic novolak type, epoxy resins of the cresolicnovolak type, epoxy resins of the phenol-aralkyl resin type, and epoxyresins of the bisphenol type;

vinyl compounds such as:

vinylbenzene, divinylbenzene, trivinylbenzene, isopropenylbenzene,diisopropenylbenzene, triisopropenylbenzene, N-vinylpyrrolidone, andN-vinylcaprolactam;

a variety of known polymerizable monomers, for example, allyl-containingcompounds such as:

 ethylene glycol diallyl carbonate, triallyl trimellitate, and triallylisocyanurate; and

 a variety of known polymerizable oligomers such as:

 polyurethane (meth)acrylates, epoxy (meth)acrylates, polyester(meth)acrylates, and polyether (meth)acrylates.

To better achieve the effects of the present invention, such apolymerizable compound may be used generally in a proportion of from 300parts by weight or less, preferably in a proportion of from 200 parts byweight or less, more preferably in a proportion of from 100 parts byweight or less per 100 parts by weight of the sulfur-containing(meth)acrylic ester compound represented by formula(1).

As a specific production process of the polymerizable compositionaccording to the present invention, it can be obtained using thesulfur-containing (meth)acrylic ester compound represented by formula(1) according to the present invention optionally in combination withone or more of the above-described various known polymerizablecompounds, adding the above-described polymerization initiator, and thenmixing them into a solution. This polymerizable composition is providedfor polymerization and curing after filtering off insoluble matter,foreign matter and the like and sufficiently defoaming the filteredcomposition under reduced pressure as needed.

Upon producing the polymerizable composition, various known additivescan be added as desired, including internal mold releasing agents, lightstabilizers, ultraviolet absorbents, antioxidants, color pigments (forexample, cyanine green, cyanine blue, etc.), dyes, flow modifiers, andinorganic fillers (for example, talc, silica, alumina, barium sulfate,magnesium oxide, etc.).

The cured product and the optical part comprising the cured productaccording to the present invention are each obtained by polymerizing andcuring the above-described polymerizable composition. As theirproduction processes, various processes known to date can be selectivelyadopted and practiced. Typically, cast polymerization or the like can bementioned. According to this process, a polymerizable compositionobtained as mentioned above is poured into a mold, and is thenpolymerized using a radical polymerization reaction which is initiatedby heat or light.

The mold is composed, for example, of two mirror-polished mold membersmade of polyethylene, ethylene-vinyl acetate copolymer, polyvinylchloride or the like and assembled together with a gasket interposedtherebetween. Examples of the mold members include the followingcombinations: glass mold member-glass mold member, glass moldmember-plastic plate, and glass mold member-metal plate. As a gasket,the above-described soft thermoplastic resin (polyethylene,ethylene-vinyl acetate copolymer, polyvinyl chloride, or the like) canbe used. As an alternative, the two mold members may be fixed togetherby a polyester adhesive tape or the like. Further, known treatment suchas mold releasing treatment may be applied to the mold members.

As mentioned above, examples of the radical polymerization reactioninclude a polymerization reaction by heat (thermopolymerization), apolymerization reaction by light such as ultraviolet rays(photopolymerization), a polymerization reaction by gamma rays, andprocesses each making combined use of a plurality of these reactions.

When polymerization is conducted by light, a cast product obtained afterparting a mold or an optical part comprising the cured product may besubjected to annealing after completion of curing such that internalstress and strain is eliminated.

Of these processes, photopolymerization by ultraviolet rays permitscuring in several seconds to several minutes as opposed tothermopolymerization that requires several hours to several tens ofhours, and therefore, is a preferred process from the standpoint ofincreasing productivity upon production of optical parts according tothe present invention.

Upon conducting thermopolymerization, the polymerization temperaturevaries depending upon the kind of the polymerization initiator and thepolymerization conditions, and no limitation is imposed thereon. Ingeneral, however, the polymerization temperature ranges from 25 to 200°C., with a range of from 50 to 170° C. being preferred.

As a molding process of an optical lens, the lens can be obtained, forexample, by conducting cast polymerization under light and/or heat asmentioned above (for example, JP 60-135901 A, JP 10-67736 A, JP10-130250 A, etc.).

Described specifically, the molding of an optical lens can be adequatelypracticed by defoaming a polymerizable composition, which has beenprepared by the above-mentioned process and contains a sulfur-containing(meth)acrylic ester compound represented by formula (1) according to thepresent invention, by a suitable method as needed, pouring it into amold, and then polymerizing it generally under irradiated light.According to polymerization under heat, on the other hand, the moldingof an optical lens can be appropriately practiced by polymerizing such apolymerizable composition while gradually heating it from a lowtemperature to a high temperature.

The thus-obtained optical lens may be subjected to annealing as neededsubsequent to its curing. If necessary, various known physical orchemical treatments can be applied further to prevent reflection, toimpart high hardness, to improve abrasion resistance, to impartanti-mist property and/or to impart fashionability, including surfacepolishing, antistatic treatment, hard coating treatment, non-reflectioncoating treatment, dyeing treatment, and photochromic treatment (forexample, treatment for the provision of a photochromic lens).

As a molding process of a substrate for an optical disk or photomagneticdisk, conventionally known processes can be mentioned including, forexample, the process in which a polymerizable composition obtained bythe above-described process and containing a sulfur-containing(meth)acrylic ester compound represented by the formula (1) is pouredinto a cavity of a disk substrate mold, is polymerized by radicalpolymerization or the like, and if necessary, is subjected to post-heattreatment (JP 58-130450 A, JP 58-137150 A, JP 62-280008 A, etc.), theprocess in which such a polymerizable composition is subjected tophotopolymerization in a mold the upper and lower walls of which aremade of glass (JP 60-202557 A), and the process in which, aftercompletion of vacuum casting or pouring of such a polymerizablecomposition, such a polymerizable composition is pressurized andthermally polymerized (JP 60-203414 A).

The cured product according to the present invention, which is obtainedby photopolymerizing the polymerizable composition, and the optical partaccording to the present invention, which comprises the cured product,are characterized in that they require several minutes to several hoursfor polymerization and curing, can be polymerized and molded in shortertime than thermosetting optical resins represented by conventionalpolydiethylene glycol diallyl carbonate and polythiourethane, and havehigh productivity.

Further, the cured product and optical part according to the presentinvention have the characteristic features that they are excellent inoptical properties, mechanical properties and thermal properties andhave high refractive indexes. Specific examples of the optical partinclude various plastic lenses typified by correctional eyeglass lenses,substrates for optical information recording media, plastic substratesfor liquid crystal cells, and coating materials for optical fibers.

The (meth)acrylic ester compounds represented by formula (1) accordingto the present invention are novel compounds each having the cyclicthioacetal structure in the molecule, and are very useful compounds asraw material monomers of resins for optical members represented bycorrectional eyeglass lenses.

The present invention will hereinafter be described more specificallybased on Examples. It should however be borne in mind that the presentinvention is not limited to these Examples.

SYNTHESIS EXAMPLE 1 Synthesis of Illustrative Compound No. 2-2 in Table2; the Compound of Formula (2-c) in Which R₁: Hydrogen Atom, R₂:Hydrogen Atom, X: Bromine Atom, m: 0, n: 2

Into a glass-made, 500-mL reactor equipped with a stirrer, ethanedithiol(25.4 g, 0.27 mole), a boron trifluoride-ether complex (25 mL) andtoluene (100 g) were charged. To the mixture,2-(2′-bromoethyl)-1,3-dioxolane (53.6 g, 0.275 mole) was added dropwiseat 20° C. over 1 hour. After the contents were allowed to react furtherat 20° C. for 5 hours, iced water (150 g) and toluene (50 g) were addedto the reaction mixture, followed by stirring for 15 minutes. Thereaction mixture was allowed to stand and separate into phases, so thatthe reaction product was extracted in the toluene phase. The toluenephase was subjected to alkaline washing with a 3% aqueous solution ofsodium hydrogencarbonate (150 g), followed by the washing with wateruntil the water phase became neutral. The toluene phase was separatedand taken out. Toluene was distilled off under reduced pressure at 40°C., and the resulting crude product was distilled under reduced pressureto afford 2-(2′-bromoethyl)-1,3-dithiolane (51.8 g) as a colorlessliquid.

Yield: 90%, purity>99% [analyzed by gas chromatography (percent by areamethod)]. Boiling point: 93 to 96° C./0.22 mmHg; ¹H-NMR δ (CDCl₃):2.2-2.3(m,2H), 3.2(s,4H), 3.4-3.5(m,2H), 4.6-4.7(t,1H). FD-MS: 212(M),214(M+2).

SYNTHESIS EXAMPLE 2 Synthesis of Illustrative Compound No. 2-18 in Table2; the Compound of Formula (2-a) in Which R₁: Hydrogen Atom, R₂:Hydrogen Atom, m: 0, n: 2

Into a glass-made, 500-mL reactor equipped with a stirrer, thiourea(32.0 g, 0.42 mole) and ethanol (175 g) were charged. To the mixture,the 2-(2′-bromoethyl)-1,3-dithiolane (44.8 g) prepared in SynthesisExample 1 was added dropwise at 50° C. over 35 minutes. The contentswere allowed to react further at 80° C. for 4 hours to yield athiouronium salt. The reaction mixture was analyzed by high-performanceliquid chromatography to confirm that the bromine-containing compound asthe raw material had been consumed up. To the reaction mixture, 18%aqueous ammonia (200 g) was added dropwise at 50° C. over 10 minutes,followed by the further reaction at 50° C. for 2 hours to hydrolyze thethiouronium salt. Toluene (100 g) was added, and the resulting mixturewas allowed to separate into phases, so that the reaction product wasextracted in the toluene phase. The toluene phase was washed with wateruntil the washing became neutral. The toluene phase was then taken out.Toluene was distilled off under reduced pressure at 40° C., and theresulting crude product was distilled under reduced pressure to afford2-(2′-mercaptoethyl)-1,3-dithiolane (31.6 g) as a colorless liquid.

Yield: 95%, purity>99% [analyzed by gas chromatography (percent by areamethod)]. Boiling point: 98 to 100° C./0.25 mmHg ¹H-NMR δ (CDCl₃):1.7-1.8 (br, 1H), 2.0-2.1 (m, 2H), 2.5-2.7 (m, 2H), 3.2-3.3 (m, 4H),4.7-4.8 (t, 1H). FD-MS: 166(M).

SYNTHESIS EXAMPLE 3 Synthesis of Illustrative Compound No. 2-32 in Table2; the Compound of Formula (2-b) in Which R₁: Hydrogen Atom, R₂:Hydrogen Atom, m: 0, n: 2

Into a glass-made, 100-mL reactor equipped with a stirrer, the2-(2′-bromoethyl)-1,3-dithiolane (21.3 g, 0.10 mole) prepared inSynthesis Example 1, sodium formate (13.6 g, 0.20 mole) andtetramethylammonium bromide (1.61 g, 0.005 mole) were charged. Themixture was stirred for 1.5 hours under heating at 110° C. Aftercompletion of a reaction, a 50% aqueous solution of sodium hydroxide(8.8 g) was added under stirring to the reaction mixture over 15minutes. The reaction product was extracted with toluene. Subsequent towashing of the extract with water, toluene was distilled off underreduced pressure at 40° C., and the resulting crude product wasdistilled under reduced pressure to afford2-(2′-hydroxyethyl)-1,3-dithiolane (13.5 g) as a colorless liquid.

Yield: 90%, purity>99% [analyzed by gas chromatography (percent by areamethod)]. Boiling point: 100 to 105° C./0.25 mmHg ¹H-NMR δ (CDCl₃):2.0-2.1 (m, 2H), 2.5-2.6 (br, 1H), 2.8-2.9 (m, 2H), 3.2-3.3 (m, 4H),4.7-4.8 (t, 1H). FD-MS: 150(M).

SYNTHESIS EXAMPLE 4 Synthesis of Illustrative Compound No. 2-5 in Table2; the Compound of Formula (2-c) in Which R₁: Methyl Group, R₂: HydrogenAtom, X: Bromine Atom, m: 0, n: 2

In a similar manner as in Synthesis Example 1 except for use of1,2-propanedithiol in place of ethanedithiol, synthesis was conducted toafford 2-(2′-bromoethyl)-4-methyl-1,3-dithiolane as a colorless liquid.

FD-MS: 226(M), 228(M+2).

SYNTHESIS EXAMPLE 5 Synthesis of Illustrative Compound No. 2-21 in Table2; the Compound of Formula (2-a) in Which R₁: Methyl Group, R₂: HydrogenAtom, p: 0, q: 2

In a similar manner as in Synthesis Example 2 except for use of the2-(2′-bromoethyl)-4-methyl-1,3-dithiolane produced in Synthesis Example4, synthesis was conducted to afford2-(2′-mercaptoethyl)-4-methyl-1,3-dithiolane as a colorless liquid.

FD-MS: 180(M).

SYNTHESIS EXAMPLE 6 Synthesis of Illustrative Compound No. 2-1 in Table2; the Compound of Formula (2-c) in Which R₁: Hydrogen Atom, R₂:Hydrogen Atom, X: Bromine Atom, m: 0, n: 1

In a similar manner as in Synthesis Example 1 except for use of2-bromomethyl-1,3-dioxolane in place of 2-bromoethyl-1,3-dioxolane,synthesis was conducted to afford 2-bromomethyl-4-methyl-1,3-dithiolaneas a colorless liquid.

FD-MS: 198(M), 200(M+2).

SYNTHESIS EXAMPLE 7 Synthesis of Illustrative Compound No. 2-17 in Table2; the Compound of Formula (2-a) in Which R₁: Hydrogen Atom, R₂:Hydrogen Atom, m: 0, n: 1

In a similar manner as in Synthesis Example 2 except for use of the2-bromomethyl-1,3-dithiolane produced in Synthesis Example 6, synthesiswas conducted to afford 2-mercaptomethyl-4-methyl-1,3-dithiolane as acolorless liquid.

FD-MS: 152(M).

EXAMPLE 1 Synthesis of Illustrative Compound No. 1-2; the Compound ofFormula (1) in Which R₁: Hydrogen Atom, R₂: Hydrogen Atom, R₃: HydrogenAtom, X₁: Sulfur Atom, m: 0, n: 2

Into a glass-made, 500-mL reaction vessel equipped with a stirrer, the2-(2′-mercaptoethyl)-1,3-dithiolane produced in Synthesis Example 2 (100g, 0.60 mole) was weighed, to which 3-chloropropionic acid chloride (80g, 0.63 mole) was added dropwise at 40° C. over 15 minutes. After thecontents were reacted further under stirring at 40° C. for 8 hours,toluene (200 g) was added to the reaction mixture to dissolve the same.The resulting solution was transferred into a separating funnel, inwhich the solution was washed three times with a 3 wt. % aqueoussolution of sodium hydrogen carbonate (300 g). After the organic layer(toluene solution) was washed with purified water (300 g) until thewater layer became neutral, the organic layer was taken out, and toluenewas then distilled off under reduced pressure to afford2-[2-(3-chloropropionylthio)ethyl]-1,3-dithiolane (127 g).

To a solution of the 2-[2-(3-chloropropionylthio)-ethyl]-1,3-dithiolane(127 g, 0.49 mole) obtained as described above and dissolved in acetone(200 g) in a glass-made 1-L reaction vessel, triethylamine (74 g, 0.73mole) was added dropwise at 25° C. over 1 hour. After the contents werestirred and reacted at 25° C. for 6 hours, toluene (400 g) and water(400 g) were added to the reaction mixture, and a toluene layer with thereaction product extracted therein was allowed to separate and was takenout. The toluene solution was washed with a 5 wt. % aqueous solution ofhydrochloric acid, and the resulting mixture was washed with water untilthe water layer became neutral. Toluene was then distilled off underreduced pressure to afford the target compound,2-(2′-acryloylthioethyl)-1,3-dithiolane, (106 g) as a colorless viscousclear liquid. Yield: 80%, purity>99% [analyzed by liquid chromatography(percent by area method)]. ¹H-NMR δ (CDCl₃): 2.0-2.1 (m, 2H), 2.5-2.7(m, 2H), 3.2-3.3 (m, 4H), 4.7-4.8 (t, 1H), 5.0-7.0 (m, 3H). FD-MS:220(M).

EXAMPLE 2 Synthesis of Illustrative Compound No. 1-44; the Compound ofFormula (1) in Which R₁: Hydrogen Atom, R₂: Hydrogen Atom, R₃: MethylGroup, X₁: Oxygen Atom, m: 0, n: 2

To a mixed solution consisting of the 2-(2′-hydroxyethyl)-1,3-dithiolane(30.0 g, 0.20 mole) produced in Synthesis Example 3, pyridine (19.0 g,0.24 mole) and chloroform (200 g), methacrylic acid chloride (19.9 g,0.22 mole) was added under ice cooling (at 10° C.). After completion ofthe dropwise addition, the contents were stirred and reacted further at10° C. for 3 hours. Byproduced pyridine hydrochloride was then filteredoff. After the chloroform solution as the filtrate was washed withdilute hydrochloric acid (200 g), the chloroform solution was washedwith water until the washing become neutral. The resulting mixture wasallowed to separate into layers, and the organic layer was taken out.Chloroform was distilled off under reduced pressure at 60° C. to obtainthe crude reaction product as a pale yellow clear liquid. The crudereaction product was purified by chromatography on silica gel to affordthe target product, 2-(2′-methacryloyloxyethyl)-1,3-dithiolane, (34.8 g)as a viscous colorless clear liquid.

Yield: 80%, purity >99% [analyzed by liquid chromatography (percent byarea method)].

¹H-NMR δ (CDCl₃):

1.9-2.0 (s, 2H), 2.1-2.4 (m, 2H), 2.5-2.8 (m, 2H), 3.2-3.3 (m, 4H),4.7-4.8 (t, 1H), 5.0-7.0 (m, 2H).

FD-MS: 218(M).

EXAMPLE 3 Synthesis of Illustrative Compound No. 1-1; the Compound ofFormula (1) in Which R₁: Hydrogen Atom, R₂: Hydrogen Atom, R₃: HydrogenAtom, X₁: Sulfur Atom, m: 0, n: 1

In a similar manner as in Example 1 except for use of the2-mercaptomethyl-1,3-dithiolane, which had been produced in SynthesisExample 7, as a raw material in place of2-(2′-mercaptoethyl)-1,3-dithiolane, 2-acryloylthiomethyl-1,3-dithiolanewas produced.

FD-MS: 206(M).

Production of Polymerizable Compositions Making use of Sulfur-containing(Meth)acrylic Ester Compounds Represented by Formula (1), and Productionof Cured Products by Their Curing

Physical properties of cured products or optical parts (lenses) producedin the following Examples and comparative example were determined by thefollowing methods.

External appearance: Tint and transparency were examined visually.

Refractive index, Abbe number: Measured at 20° C. by using a Pulfrichreflectometer.

Impact resistance: Determined by dropping a steel ball from a height of127 cm onto a central part of each minus lens the center thickness ofwhich was 1.5 mm.

EXAMPLE 4

To the sulfur-containing acrylic ester compound (Illustrative CompoundNo. 1-2; 30 g) obtained above in Example 1,2-hydroxy-2-methyl-1-phenylpropan-1-one (“Darocur-1173”, product ofCiba-Geigy AG; 30 mg) was added as a photopolymerization initiator. Theywere thoroughly mixed into a solution. After defoamed under sufficientlyreduced pressure, the solution was poured into a mold unit composed ofglass mold members and a gasket. Using a metal halide lamp (80 W/cm),ultraviolet rays were irradiated for 60 seconds to effectpolymerization. After completion of the polymerization, thepolymerization product was allowed to gradually cool down, and thethus-molded, cured product was taken out of the mold unit.

The thus-obtained cured product was colorless and transparent, and nooptical strain was observed. Its refractive index was 1.645 (nd), andits Abbe number was 36 (vd).

EXAMPLE 5

Preparation of a polymerizable composition and its polymerization underlight (ultraviolet rays) were conducted in a similar manner as inExample 4 except for use of the sulfur-containing (meth)acrylic estercompound, which had been produced as Illustrative Compound No. 1-44 inExample 2, in place of the sulfur-containing (meth)acrylic estercompound as Illustrative Compound No. 1-2.

The thus-obtained cured product was colorless and transparent, and nooptical strain was observed. Its refractive index was 1.615 (nd), andits Abbe number was 37 (vd).

EXAMPLE 6

Preparation of a polymerizable composition and its polymerization underlight (ultraviolet rays) were conducted in a similar manner as inExample 4 except for use of the sulfur-containing (meth)acrylic estercompound, which had been produced as Illustrative Compound No. 1-1 inExample 3, in place of the sulfur-containing (meth)acrylic estercompound as Illustrative Compound No. 1-2.

The thus-obtained cured product was colorless and transparent, and nooptical strain was observed. Its refractive index was 1.660 (nd), andits Abbe number was 35 (vd).

The sulfur-containing (meth)acrylic ester compounds according to thepresent invention were curable (photo-polymerizable) by irradiation oflight for short time. Further, the resultant cured products each had ahigh refractive index and a high Abbe number and was good in heatresistance and impact resistance.

EXAMPLE 7

To a mixture consisting of the sulfur-containing (meth)acrylic estercompound (20 g) obtained as Illustrative Compound No. 1-1 in Example 3and the epoxy acrylate of bisphenol A diglycidyl ether (5 g),2-hydroxy-2-methyl-1-phenylpropan-1-one (50 mg; 0.2 wt. % based on theweight of the polymerizable compound) was added. The resulting mixturewas thoroughly stirred into a solution. Subsequent to thoroughdefoaming, the resultant liquid was poured into a mold unit composed ofglass mold members and a tape and formed to define the shape of a minuslens. After ultraviolet rays were irradiated for 60 seconds by a metalhalide lamp, annealing was conducted at 80° C. for 1 hour. Aftercompletion of polymerization, the polymerization product was allowed tocool down to room temperature to obtain a colorless transparent minuslens having a diameter of 30 mm and a center thickness of 1.5 mm.

The lens was colorless and transparent, its refractive index and Abbenumber were 1.645 (nd) and 35 (vd), respectively, and its heatresistance and impact resistance were good.

INDUSTRIAL APPLICABILITY

Cured products and optical parts, which can be obtained by polymerizingpolymerizable compositions containing sulfur-containing (meth)acrylicester compounds according to the present invention, respectively, areexcellent in optical properties, thermal properties and mechanicalproperties (impact resistance), have high productivity owing toshort-time polymerization and curing moldability, and have highrefractive indexes.

The sulfur-containing (meth)acrylic ester compounds according to thepresent invention are very useful, as monomers for photocurable,polymerizable compositions, in applications such as optical materialsand dental materials. Optical parts obtained by curing the polymerizablecompositions are excellent in optical properties, thermal properties andmechanical properties, are good in productivity and have high refractiveindexes, so that they are useful as various plastic lenses representedby correctional eyeglass lenses, substrates for optical informationrecording media, plastic substrates for liquid crystal cells, coatingmaterials for optical fibers, and the like.

What is claimed is:
 1. A sulfur-containing (meth)acrylic ester compoundrepresented by the following formula (1);

wherein R₁ and R₂ each independently represent a hydrogen atom or analkyl group or may be fused together to form a ring, R₃ represents ahydrogen atom or a methyl group, X₁ represents a sulfur atom, m standsfor an integer of from 0 to 3, and n stands for an integer of from 1 to4.